Cylinder honing



June 1943- v. w. PETERSON EI'AL 2,320,747

CYLINDER HONING Filed Dec. 29, 1938 2 Sheets-Sheet l W o 6 m June 1943-v. w. PETERSON El'AL 2,320,747

CYLINDER HONING Filed D ec. 29, 1938 2 Sheets-Sheet 2 Patented June 1,1943 CYLINDER. HONING victor W. Peterson and Frank J. Daley, Chicago,

Ill., assignors to Hannifin Manufacturing Company, Chicago, 11]., acorporation of Illinois Application December 29, 1938, Serial No.248,213

Claims.

This invention relates to honing of cylinders and the like, and amongother objects aims to provide an improved and simplified apparatus forforming straight and true cylinder bores.

The nature of the invention may be readily understood by reference toone illustrative apparatus and its method of use shown and described inthe drawings and accompanying specification,

In said drawings:

Fig. 1 is a longitudinal section (taken on the broken plane Il of Fig.2) of a honing tool in position inside a cylinder to be honed; and

Fig. 2 is a transverse section taken on the broken plane 22 of Fig. 1.

As applied to cylinders and the like, honing may be employed to form notonly a smooth or polished cylindrical bore but one accurate to afraction of a thousandth of an inch both in diameter and straightness.The honing operation is characterized by the simultaneous reciprocationand rotation of a hone through the cylinder bore. For best results,there should be a definite relation between the rates of rotation andreciprocation of the hone. Preferably these rates should be such thatthe helical marks or scratches formed by the hone on its forward strokeshould cross those formed on the return stroke at angles between 40 and60".

In general, the honing tool comprises a series of elongated stones,preferably arranged parallel to the axis of the bore and radiallypressed outwardly against the cylinder wall. It is important that thepressure of the stones against the cylinder wall be uniform and constantdespite the wearing away of the cutting stones and removal of metal.Under these conditions, high and low spots in the cylinder will beremoved and the bore made straight and true.

Originally honing was employed principally as a finishing operation orto remove only very slight irregularities or out-of-round conditions.Substantial high spots" resulted in excessive stone breakage. Otherincidents of prior practice were excessive time required for the honingoperation and the necessity for frequent adjustment of the hone. All ofthese diificulties were magnified in honing long cylinders.

Since the rate at which metal is removed depends upon the rate at whichthe cutting stones are broken down (to expose fresh cutting points), theproblem of maintaining adequate uniform and constant. pressure of thestones against the metal and avoidance of breakage of the stones on highspots is a substantial one.

In the illustrative hone, adequate uniform and constant pressure ismaintained despite the wearing of the stones without the necessity offrequent adjustment of the tool and without danger of breakage of thestones. This result is obtained by pressing the stones outwardly bypneumatic pressure applied, in this instance, by a flexible tube l 0,extending longitudinally inside the honing tool II and inflatedsufiiciently to apply the desired stone pressure.

As here shown, the honing stones l2 are rigidly mounted on a pluralityof carriers in the form of plungers l3 slidable in outwardly directedbores M in the cylindrical body l5 of the tool. The bores need not beradial. If they be at an angle to the radius,'the effective width of thecutting face of the stones is increased somewhat. Preferablythe plungersproject into the central bore iii in which the inflated tube lies,sufficiently to bring the plunger into efiectivc contact with theinflated tube and to provide a substantial range of radial movement ofthe plungers (without obliging the flexible tube to expand into thebores M) to adapt the tool to a substantial range of bore diameters. Therange of tool diameters may be increased if the plungers be notdiametrically opposite but are staggered so that for small bores theirends may project inwardly beyond the axis of the tool. The same tool maybe used on still larger bore diameters simply by employing a longer setof carrier plungers I3. This is a very substantial advantage since itavoids the necessity of carrying a series of complete tools for varyingbore diameters.

The number of sets of cutting stones may, of course, be varied. Six arehere shown, each set mounted on three plungers. Preferably the bore Mare lined with removable bushings I! to maintain a close sliding fit forthe plungers and thereby prevent lateral play through wear.

The stones may be mounted on the carrier plungers in various ways. Ashere shown, the plungers support a rigid channel I8 seated in channelshaped recesses I9 in the enlarged extremities 20 of the plungers.Screws 2| hold the channel in place. The honing stones l2, in this casetwo for each set, are conventionally cemented or otherwise securedinside sheet metal channels 22 held by screws 23 inside the mainchannels l8. The character of the stones varies according to thecharacter of the metal honed, the desired rate of cutting, the finishdesired, etc.

The tube l0 may be made of a variety of materials but it is advantageousto employ an oil resisting synthetic rubber, such as chloroprene rubber.One rubber of this character is sold on the market under the trade-nameneoprene." The ends 24 and 25 of the tube are supported against heads 26and 21 closin the ends of the central bore l6 of the tool. The heads areremovably attached to the body l by screws 28. The forward head 21 inthis instance is formed integral with the operating shaft 29 by whichthe tool is rotated and reciprocated. In this connection it should beunderstood that the tool and its shaft are not rigidly connected to thedriving means but have a floating" connection which enables the toolfreely to follow the cylinder bore.

A passage 30 is provided in the shaft and head for the valve stem 3|.The valve stem may be an ordinary automobile tire tube valve stemconnected to the tube in the conventional way and provided with aconventional valve. Other means may, of course, be used for maintainingand regulating the air pressure. The tube walls in this instance arapproximately 1% of an inch in thickness and are capable of carrying thepressure without danger of breakage even at the points 32 adjacent theends of the plungers.

Various grades and types of stone, each suited to a particular metal oroperation, are available on the market.

For removing metal at the maximum rate, it is desirable to operate withstone pressures as high as practicable, limited only by the ability ofthe chuck or other work ripping means to hold the cylinder withoutturning or without distorting the cylinder walls. It should beunderstood, however, that different pressures are generally required fordifferent types of stone and difierent types of work. For low carbonsteel, stone pressures of 50 to 80 pounds per square inch aresatisfactory. In the illustrative apparatus (wherein the stones are 6"long and /2" wide and the carrier plungers are 1 in diameter), airpressure of 65 pounds per square inch would produce a stone pressure ofabout 40 pounds per square inch. Higher pressures are generallyemployed.

Unlike pressure produced by springs, the stone pressure in theillustrative apparatus is uniform and constant for all stones and radialpositions of the plungers and regardless of stone wear. Nevertheless,the pressure may be easily changed. It may be made much higher than anyspring of a size adapted to the tool could exert. The pressure can beeasily released to remove and insert the tool.

The cutting stones are advantageously provided with means for moving thesame inwardly when pressure is released to permit the easy withdrawaland insertion of the tool. The means here show-n are in the form ofsprings 33 whose ends are connected to clips 34 attached to the underfaces of the channels l8.

In using the tool, the same is first inserted inside the bore to behoned and thereafter the tube is inflated to the desired pressures. Thepressure on the stones is thus maintained uniform and constantthroughout the operation regardless of the wearing of the stones or theradial position of the ends of the plungers. There are, therefore, noperiods (due to reduction in pressure through stone wear as in otherdevices) at which the tool is not operating at maximum efficiency, thatis, removing metal at the maximum rate. The ability of the stones toyield inwardly when striking a high spot makes it possible to usemaximum pressures without danger of stone breakage, thereby reducing thehigh spots with maximum speed. Moreover, it is possible to regulatepressures exactly to those required for best results and exactly toduplicate conditions for similar kinds of work. Heretofore it has beenimpossible either to determine or regulate stone pressures or toduplicate conditions. In the present apparatus once the pressure hasbeen set it is applied equally to all stones regardless of differentrates of wear; it is uniform throughout the entire length of thecylinder regardless of wear and remains constant throughout the entireoperation.

The light weight of the illustrative hone (about one-third that of thetools heretofore employed) is of substantial advantage in horizontalhoning operations, such as honing long cylinders. It is unnecessary toturn the cylinder repeatedly to compensate for the greater cutting rate(of a heavy tool) at the lower part of the cylinder.

For most cylinders, and particularly long cylinders, it is generallypreferable to precede the honing by aboring operation. The combinedoperations take less time and are less expensive.

Obviously the invention is not limited to the details of theillustrative embodiments thereof herein disclosed, since these may bevariously modified. Moreover it is not indispensable that all featuresof the invention be used conjointly since various features may be usedto advantage in different combinations and sub-combinations.

Having described our invention, we claim:

1. A device for forming true round and straight bores in cylinderscomprising in combination a rotary and reciprocating tool body, aplurality of longitudinally extending honing means radially slidable insaid body and each honing means being slidable independently of theother, a flexible impervious tube inside said body bearing against saidhoning means, said tube having therein a volume of gas such as air undersubstantial compression to force said honing means outwardly underresilient pressure, the volume of compressed gas inside said tube beingsuflicient to maintain substantially constant pressure against thestones throughout the honing operation despite stone wear during honing.

2. A device for forming true round and straight bores in cylinderscomprising a rotary and reciprocating tool body having a hollowinterior. a plurality of longitudinally extending honing means radiallyslidable in said body independently of each other, an elastic pneumatictube in said interior, a volume of gas under pressure inside said tubeto cause said tube to bear against said honing means to force the sameoutwardly against the work under honing pressure, the volume of saidcompressed gas inside said tube being sufiicient to maintainsubstantially constant pressure against the stones throughout the honingoperation without reduction on account of stone wear.

3. A device for forming true round and straight bores for cylinderscomprising a rotary and reciprocable tool body having a hollow interior,stone mounting means slidable in and out of said body and carryinghoning stones, a. flexible pneumatic tube inside said hollow interiorand adapted to bear against said stone mounting means, a volume ofcompressed gas inside said tube for causing the latter to press saidstone mounting means outwardly under honing pressure, means for sealingsaid tube to prevent accidental escape of gas, the volume of saidcompressed gas being suflicient to maintain substantially constantpressure against the stone mounting means throughout the honingoperation despite stone wear.

4. A device for forming true round and straight bores for cylinderscomprising a rotary and reciprocable tool body having a hollow interior,stone mounting means slidable in and out of said body and carryinghoning stones, a flexible pneumatic tube inside said hollow interior andadapted to bear against said stone mounting means. a volume ofcompressed gas inside said tube for causing the latter to press saidstone mounting means outwardly, means for introducing compressed gasinto said tube, said means permitting variation in the volume of gasintroduced to regulate the desired stone pressure, the volume of saidcompressed gas in said tube being sufficient to maintain substantiallyconstant stone pressure throughout the honing operation despite stonewear.

5. The method of straightening and rounding the bores of long cylinderswhich is characterized by reciprocating and rotating three or morecircumferentially spaced honing stones throughout the bore of thecylinder, pressing the stones outwardly by a sealed volume of air underpressure inside the bore behind the stones to secure uniform stonepressure throughout the length of the cylinder, the volume of air underpressure being suflicient to maintain a substantially constant stonepressure throughout the honing operation without reduction on account ofstone wear, and allowing each stone to yield inwardly independently ofthe other stones when encountering a high spot on the bore whilemaintaining uniform air pressure on other stones.

VICTOR W. PETERSON. FRANK J. DALEY.

